reflection - Change struct tag (xml) at runtime -

there's struct:

type s struct {   value string `xml:"value,attr"` } 

i want encode struct xml file. however, want attribute name of value different in each file:

s1 := s{   value: "one" } 

should encode to:

<s value="one"></s> 

and

s2 := s{   value: "two" } 

should encode to:

<s category="two"></s> 

so, need either change xml element name somehow, or change tag on field. possible?

i checked reflect (https://golang.org/pkg/reflect/#value.fieldbyname), since fieldbyname returns value type , there no set methods, don't think it's possible use reflection.

(i don't know why did other person delete answer, here's mine.)

you can either use combination of ,attr , ,omitempty

type s struct {     value    string `xml:"value,attr,omitempty"`     category string `xml:"category,attr,omitempty"` } 

(playground: http://play.golang.org/p/c9trla80rv) or create custom xml.marshalerattr

type s struct {     value val `xml:",attr"` }  type val struct{ string }  func (v val) marshalxmlattr(name xml.name) (xml.attr, error) {     if v.string == "one" {         return xml.attr{name: xml.name{local: "value"}, value: v.string}, nil     }      return xml.attr{name: xml.name{local: "category"}, value: v.string}, nil } 

(playground: http://play.golang.org/p/a1wd2gonb_).

the first approach easier less flexible, , makes struct bigger. second approach more complex, more robust , flexible.